Double current telegraph installation



ISIEGFRIED CHHN Jul 57,1936, M. AMANN ET AL DOUBLE CURRENT TELEGRAPH INSTALLATION Filed May 17, 1935 Patented July '7, 1936 UNITED STATES PATENT OFFICE DOUBLE CURRENT TELEGRAPH INSTALLATION Max 'Amann and Siegfried Cahn, Frankfort- 'on-the-Maln, Germany Application May 17,1935, Se 1 No. 22,160 In Germany May 19, 934

9 Claimi. ('CI. 178 2) This invention relates to double current telegraph installations in which a battery for supplying what-is called a marking current to the line is connected to the line at each end through a polarized receiving relay. In such telegraph installations, during the sending of the current signals effected by the transmitting contact, a

spacing battery is connected to the line at the transmitting station which acts in opposition to the markingbattery at the other end of the line and transmits a spacing current through the line in a direction opposite to that of the marking current. The voltage of this spacing" battery is considerably greater than that of the marking battery at the same station so that in the receiving relay of the station at the other .end of the line, the marking current and the spacing current are approximately. equal. These spacing and marking currents which 0 canbe made to flow in either direction also flow through the receiving relay of the transmitting by it and by the winding connected to thelinestation but the spacing current at this end of the line, in consequence of the leakage losses along the line and the larger voltage of the "spac- 'ing battery, is substantially greater than the "marking current. The sensitive receiving relay of the transmitting station cannot, therefore, operate correctly during the signal transmissionso as to transmit the signal combination. The transmitted text cannot, therefore, be recorded.

In order that the relay at the sending station. may operate correctly, according to the invention, 4

the relay is provided with a second winding which is switched in when the (:spacing battery is switched in. This secondwinding can be so designed that the resulting magnetic flux produced.

is of the same size as and acts in the opposite direction to the magnetic 'flux which is produced by the line winding ,of the relay when it is energized merely by the marking current An example of a telegraph installation in accordance with the invention is illustrated in the accompanying drawing. A telegraph installation is shown having two stations A and B which are connected together by a lineL. Both stations are fitted out so that they can be used at any time for the transmission through the line of signals composed of five current signals. The drawing only illustrates those parts of the system at the two stations which are essential for the invention. The type of mechanical control used for .the transmitting contact has been indicated only .in the station B. w

The line L is subdivided into two sections La relays at each station.

and Lb which are coupled together through a repeater U.

- The telegraph apparatus of the station A is provided 'with a set of transmitting contacts 8, comprising a contact ss, which is normally closed, 5 for transmitting the start and stop signals and, parallel to this contact, five selectable contacts 1-5 which'can be closed in sequence fortransmitting the five current impulses. Such sets of transmitting contacts are known in telegraph 943- .10

In the station A, an earthed spacing battery BAl is also provided which is of at least double 7 the voltage of the battery Brl or Brl'; having 5 regard to the loss of current through leakage along the line, the spacing" battery trequently has to have a considerably higher voltage. The spacing battery Bal can be connected in opposition to the marking" batteries Brl and Brl'.

In the normal condition, the battery Bal is disconnected at the contact at in order to save current; The contact u is controlled by a cam disc N which can be flxed'to the (unillustrated) shaft ol,the transmitting distributor. As this transmitting distributor shaft makesga single revolution every time a. signal is transmitted, the contact u will also be closed once every time a signal is transmitted. A protective resistance Rel prevents the occurrence of high short circuit our- 4.0 rents when the contacts of the set S and the contact u are simultaneously closed. r

The line relay El has, in addition to the line winding 1, a counterwinding g which can be short circuited by the contact ss and by the contacts S 1-5, after the contact alias been closed at the beginning of the revolution of the transmitting v distributor shaft. This counter winding g is connected in series with the regulating-"resistance Ra1 and is so'designedthat when short circuited,

there-is practically'no appreciable delay in the operation of the relay El due to the signal received through the winding 1. I! the short circuiting of the winding g is removed by opening the contact ss (for example, during the start V winding 1. It flows, however, in the opposite-direction to the latter flux.

The relay EI is constructed as a polarized relay. By means of its contact eI, it controls local circuits and in particular, the circuit which includes the receiving magnet EMa of the telegraph apparatus of the station A.

The telegraph apparatus of the station 13 includes a set of contacts K comprising a transmitting contact 8 which is normally closed and a further contact w. The set of contacts K is controlled through a control lever H by the cams St, I to 5 and Sp of a rotary cam switch V. The cams St and Sp come into use for the start and stop current signals while the cams I to 5 are differently set according to the operation of the keysT of a key board and thus determine the five current impulses. The cam switch V is released by means of a start stop coupling P at each signal transmission for one complete revolution. The construction of such a cam switch is described in detail in Patent No. 1,983,960. The transmission contact s is in the steady marking" circuit which includes the earthed marking current battery Br2, the winding l of the receiving relay E2, the line section Lb, the contact ea, the relay Eb oi the repeater U and the, marking" battery 131-2. The two batteries are connected in series and are of equal size. The earthed spacing battery Ba! of the station B has a considerably higher voltage than the "marking" batteryv Br2. The protective resistance Rn! allows the flow of currentrrom the spacing" battery to be regulated in accordance with, the leakage occurring in the line section Lb. The spacing battery Be! is connected by means of the contact to every time the set of contacts K is reversed. The set of contacts K is constructed as a make-before-break contact so that the contact w is closed at least for the duration 01 the opening of the contact s. I I

The relay E2 has a counter winding 9 which works similarly to the counter winding of the relay EI.

The repeater Uha's, in addition to the polarized relays Ea, Eb connected in series through the earthed marking" batteries Brl', BrZ', a spacing battery Bu which, similarly to the spacing" batteries BaI and Ba! has a considerably higher voltage (at least twice as high) as the marking batteries B11 and Brl". This spacing" battery Bu is earthed with opposite potential. In the spacing? current circuit there are a'neutral relay M and a resistance RU. The relay M through its contact m controls a' local circuit in which, for example, the receiving magnet EM of a recording device or a switching device lies. The relays Ed and Eb are electricallypolarized by a constant flow current through the resistances Wu and Wb.

The manner of operation of the arrangement,

J is as follows:

Let it be assumed that signals are to be transmitted from the station A to the station B and that the apparatus of both stations is ready for operation. At the beginning of the transmission, the state of aflfairs is as illustrated; the relays El and Ea, as well as the relays Eb and E! are energized and maintain their armatures in the illustrated normal position. A steady "marking curto overcome the counter voltage of the marking battery BrPof the repeater U. The "spacing current supplied from the battery BaI reverses the polarity oi. the repeater relay Ea so that the latter throws its contact ea. The relay Eb remains under the influence of the current flowing through the resistance Wb in spite of being switched from the line section Lb into the illustrated position.

The contact ea. opens the steady marking." circuit through the line section Lb and connects the counter voltage of the "spacing battery Bu to the line. The voltage of the battery Bu overcomes the voltage of the marking battery 311. The spacing" current from the battery Bu now flowing in the opposite direction to the marking so that the lattenreverses its armature and interrupts the circuit for the receiving magnet EMb.

During the section following the start section of the signal, the contact I of the set of transmitting contacts S of the station is opened or closed according to'the signal to besent. Ii it is opened, then the state of aflfairs described above is maintained through the opening-of the contact ss. If, however, it is closed, then the marking" battery B11 is again connected directly to the winding 1 of the relay El and the line section La. Althoug'h the spacing battery BaI is connected in parallel with the battery Bri through the contact a, no spacing current can flow through me line because the spacing battery lies in series with the resistance Ball. All

the relays have their polarities reversed again by the marking currentso that their contacts are returned into the illustrated position.

In this way, at each sequence of openings and closings of the transmitting contact, the magnet EMb is correspondingly influenced which causes the signal sent from the station A to beprinted in known manner in the station B.

In order that the relay El, the winding 1 oi which is traversed, when the transmitting contact at the station A isppened, by a current from the spacing current battery Bai which is considerably larger than the marking current, may follow the double current impulse tree from distortion, the transmitting contact each time it is opened will also switch in the counter winding g. The m etic flux produced by the two windcurrent energizes the winding 1 oi. the relay E3 means of the adjustable resistance Rgl.

- is thus produced.

In the repeater U, the relay M is intermittently energized during thesignal transmission and controls the magnet EM through its contact m.

During the stop section at theend of each transmitted signal, the apparatus is againbrought'into the illustrated normal position.

Y The system operates in a like manner for the transmission of signals from the station B to the station A. In the station B, however, without in this way introducing. any difierence as regards the flow of current to the line, the spacing battery Ba2 is nowalways switched in for one signal section by means of the set of make-before-break contacts K and thus is onlyshort circuited for a short time for the duration of the simultaneous closing of the contacts s and w; In

contrast to the system at the station A in,

which the spacing battery Bal is also short circuited for the feed current signal elements through the resistance Ral, a saving in current The resistance Ral and Ra! are adjustable and the voltages of the spacing batteries Bal and 3112 are adapted to the leakage conditions in the line sections. also adjustable. 'They determine the size of the current flowing through the counter winding of the receiving relays, The resistances Rat and 'Rgi can also be made adjustable in common as is shown in the case of the station A.' Thus the adjustment of the voltageof the spacing 'current and 'of the current flowing through the counter-winding of the relay at the transmitting station, according to the leakage of the'line at each moment, is very much simplified.

As the spacing" battery, the voltage of the battery Bu of the repeaterU must be adapted to the leakage conditions in the line sections La and Lb. This is efi'ected by means of the adjustable resistance RU. The adjustment of the resistance can be undertaken by hand by a supervisor according to the needs of the transmitting station A or B which are recorded at the repeater receiving apparatus. They can be adjusted by remote control by means of the magnet EM. In most cases it is sufficient to providea single resistance RU; a suitable separate resistancecould also, however, be provided for two line sections.

We claim:--"

' 1. A double current telegraph installation comprising two stations, a line betweensaid stations, a polarized receiving relayat each station connected to said line, a marking battery at each station connected through said receiving relay to said line and the marking batteries of the two stations being connected in series allowing a steady marking current to flow over the line and said receiving relays at each station, a spacing battery at one of said stations of higher voltage than the markingbattery, a transmitting contact at said last mentioned station adapted to make said spacing battery effective for sending a spacing current in a direction opposite to the direcceiv'i-ng relay being provided with a plurality of windings, one of which windings is connected to said line and to said transmitting contact and another being connected to said spacing battery.

2. A telegraph installation according to claim 1, in which the second winding of said receiving relay is designed so that the magnetic flux produced by it and by the line winding .due to their energization by the spacing current is equal to The resistances Rgl and By! are and acts in opposition to the magnetic flux which is produced by the line winding of the relay due to its energization only by the marking current.

3. A double current telegraph installation, comprising two stations, a line between said stations,

a polarized receiving relay at each station, a mark ing battery at one'of said stations, a spacing battery at one of said stations having a higher voltage than said marking battery, a transmitting contact at said last mentioned station adapted to makesaid spacing battery effective, said polarized receiving relay being provided with a plurality of windings, one of which windings is connected to said line and to-said transmitting contact and another being connected to said spacing battery and being so designed that when short circuited, the operation of said relay is not delayed, said, transmitting contact being adapted normally to' short circuit that winding of said relay which'is connected to said spacing battery.

4. A double current telegraph installation, comprising two stations, at line between said stations, a polarized receiving relay at each station, a marking battery at each station connected through said receiving relay to said line and the marking batteries at the two stations being connected 'in series allowing a steady marking current to flow-over the line and said receiving relays at each station, a spacing battery at one of said stations,-a transmitting contact at the last mentioned station adapted to make said spacing battery effective, an adjustable resistance included in the circuit of said spacing battery, said spacing battery having a higher voltage than the markingbattery, said polarized receiving relay beingprovided with a plurality of windings, one of which windings is connected to the line and to the transmitting contact-and another to said lays at each station, a spacing battery at one of said stations having a larger voltage than the marking battery, a transmitting contact at'said last mentioned station adapted tov make said spacing battery efiective, said polarized receiving relay being provided with a plurality=of windings, one of said windings being connected to the line and to the transmitting contact and another being connected to said spacing battery, and an adjustable resistance in the circuit of the winding connected to'said spacing battery.

6. A double current telegraph installation COIl'l-r prising two stations, a line between said stations,

a polarized receiving relay at each station, a marking battery at each station connected to the said line, a spacing battery at one of said stations having a larger voltage than the marking battery at either station, a transmitting contact at thelast mentioned station adapted to make said spacing battery efiective, and an adjustable resistance in the circuit of said spacing battery, said polarized receiving relay being provided with a plurality of windings, one of said windings being connected to said lineand to said transmitting contact and another being connected to said spacing battery and an adjustable resistance in the circuit of the winding connected to said spacing battery, the

two named adjustable resistances being constructed so as to be controlled in common. 7. A double current telegraph installation comprising two stations, a line between said stations, said line being subdivided into two sections,-a repeater connected between said sections, .said repeater comprising two relays, two marking batteries, each of said marking batteries being connected through one of said relays to one section of the line, a spacing battery, and contacts controlled by each of said relays, the contacts connected through one of said relays to one section I v of theline, a spacing battery, a relay connected in series with said spacing battery and contacts controlled by each of said relays connected to the marking batteries, the contacts controlled by the relay connected to the first section of the line being adapted to connect said spacing battery with the second section of the line and vice versa.

9. A double current telegraph installation, comprising two stations, a line between said stations, said line being subdivided into two sections, a repeater connected between said sections, said repeater comprising two relays, two marking bat teries, each of said marking batteries being connected through one of said relays to one section of the line, a spacing battery, a'relay connected in series with said spacing battery, an adjustable resistance connected in series with said spacing battery, and contacts controlled by each of said relays connected to the marking batteries and adapted to connect said spacing battery to said sections of the line. 4 

